David Jones is to stand down as the global chief executive of French advertising group Havas, and will be replaced by the son of controlling shareholder Vincent Bolloré.

Jones, who has held the top Havas role since 2011, is leaving the sixth largest global advertising group to become co-founder and chief executive of a new tech startup focusing on social responsibility and social media.

Bolloré, the largest shareholder in Havas with a 37% stake, named his 33 year-old-son Yannick as Jones's replacement.

Yannick Bolloré is already the company's chairman, replacing his father in that role last year after Vincent became Vivendi chairman. At the same time he appointed his other son, Cyrille, as his second in command at family business Bolloré Group.

Bolloré signalled his intention to increase the family influence over the Havas business last June.

Jones leaves his position with immediate effect but will be retained as adviser to Yannick Bolloré for the rest of 2014.

"If I were going to stay in the industry it would be at Havas, but I have always had a burning desire to be an entrepreneur and this is too exciting an opportunity to not seize," he said. "Those people who know me know my two passions in business are social media and social responsibility and this new venture combines the two."

Andrew Benett, co-president of Havas Worldwide, has been promoted to chief executive of the advertising network and will report to Yannick Bolloré.

"It's a very exciting time for Havas," said Yannick Bolloré. "We are well on our way to realising our goal of being the most integrated and innovative communications group of our industry. I would like to thank David for the impact he has made at Havas over the last 15 years."

Patrick Kirby, a Deutsche Bank analyst, said Jones's departure was a "near-term disappointment", particularly given Havas also lost chief financial officer Hervé Philippe last month when Bolloré moved him to Vivendi.

Bolloré had once harboured ambitions of making Havas a top-tier global advertising player by merging with UK media buying group Aegis, in which he took a significant stake.

However, in July 2012 Japanese group Dentsu put paid to years of Havas merger speculation by buying Aegis in a £3.2bn deal. Bolloré made £743.8m gross selling his 26.4% stake in Aegis, netting €450m profit from his original investment.

The impending merger of French rival Publicis Groupe with US company Omnicom, to create the world's largest advertising group, has sparked speculation over the future of Havas.

Thomas Singlehurst, a Citigroup analyst, said that the increased operational control of Havas by the Bolloré family "probably only confirms the 'a priori' reality" of the power it has with a 37% stake, "while also potentially increasing the chance of mergers and acquisitions".

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